Compressor installation



'Dec. 16, 1924-. 1519;449-

B. GRAEMIGER COMPRESSOR INSTALLATION Filed May 14, 1923 Patented Dec. 16, 1924.

UNITED STATES PATENT OFFICE.

BENJAMIN GRAE-MIGER, O'IE ZURICH, SWITZERLAND, ASSIGNOR TO AKT'IENGESELL- SCI-IAFT DER MASCHINENFABRIKEN ESCHER WYSS & CIR, OF ZURICH, SWITZER- LAND.

COMPRESSOR INSTALLATION.

Application filed May 14,

To all whom it may concern:

Be it known that I, BENJAMIN GRAEM} GER, a citizen of the Republic of Switzerland, residing at Zurich, Switzerland, have invented certain new and useful Improvements in Compressor Installations, of which the following is a specification, reference being had therein to the accompanying drawing.

The subject matter of the present invention is a compressor installation, comprising at least one main compressor and at least one additional compressor adapted to work in series with the main compressor for the purpose of obtaining a higher pressure, being a construction different from the construction of my Patent No. 1509351 dated September 23, 19st.

Compressor installations are often required to deliver periodically an essential higher pressure than normal pressure, in which case the quantity delivered will of course be smaller than the normal quantity. This is for instance the case with blast-furnace blowing installations which normally work with a discharge pressure of, for'instance, 0.8 atmospheres above atmospheric. In some cases (hanging of the charge), however. a great increase in the pressure up to double the normal pressure is required, whereby the quantity of air may decrease to a large extent. This manner of working, however, occurs con'iparatively seldom, so that it is justified to take care that above all the normal working of such installations is as efficient as possible. Vith compressors running at a constant speed ('electromoter driven compressors) an increase in pressure above the normal pressure cannot be obtained, unless the compressor is so constructed that it yields a low efficiency at normal working. But also with installations adapted to run at variable speed (turbine driven compressors) turbine and compressor yield a low efficiency at normal working if the compressor is so designed as to be able to discharge periodically at a pressure that is greater than the normal pressure.

In order to respond to the above mentioned requirements without having to put up with the drawbacks referred to, the additional compressor of an installation of the aforementioned type working in series with the main compressor is driven according to the present invention by a prime mover in 1923. Serial N0. 638,885.

which part of the medium delivered by the main compressor expands to the delivery pressure of the additional compressor whereupon this part, together with the medium delivered by the additional compressor, is returned to the main compressor.

constructional examples of the subject matter of the present invention are illustrated on the accompanying drawings, in which Fig. 1 shows an installation according to the invention and Fig. 2 shows part of the construction of the additional compressor and the power engine driving the former.

In the installation illustrated in Fig. 1, 1

denotes the main compressor driven by a power engine 2 of any suitable type. 3 designates the suction conduit and 4: is the pressure conduit of the main compressor. A valve 13 is inserted in the suction conduit 3. The additional compressor 5 is driven by a power engine 6 and is provided with a suction conduit 7 and a pressure conduit 8. The power engine 6 driving the additional compressor 5 is connected to the pressure conduit 4 by means of a conduit 9 in which a valve 10 is inserted. A conduit 11 which joins to the conduit 8 forms a connection between the exhaust of the power engine 6 and the suction conduit 3, a valve 12 being provided in this connection;

During the normal working the valve 13 is open and the valves 10 and 12 are closed. The main compressor 1 delivers thereby the medium sucked through the conduit 3 into the conduit 14: leading to a place of consumption which is not illustrated in the drawings.

hen an increase in pressure is desired the valve 13 is closed and the valves 10 and 12 are opened. Part of the medium delivered by the main compressor enters now the power engine 6 driving the additional compressor 5, in which it expands to the dis charge pressure of the additional compressor and transmitting thereby useful work, whereupon it is returned together with the medium delivered by the additional compressor 5 to the main compressor in which it is compressed together with that medium to a higher pressure than the pressure at normal working.

Assume valve 13 closed and valves 10 and 12 to be open, a condition of operation ex- IOU ists such that the resistance in conduit 1% decreases. This results in an increase in the demand on the compressor 1. With an increase in the quantity of air to be delivered the pressure decreases, as is characteristic of centrifugal compressors, and consequently the turbine 6 delivers little power, resulting in a lower pressure delivered by the compressor than at first, especially as the demand in air volume is greater.

The counter pressure in 11 decreases, .permitting more air to pass through IO, so that the entire mechanism always tends to regulate itself. 7

The greater delivery through 14 immediately and automatically results in a smaller delivery through '9 with the necessary smaller pressure.

On the other hand, it the pressure at 14 increases, the pressure in 1, by reason of the smaller volume of discharge, increases.

The air turbine 6 receives driving medium of greater pressure, and its power increases, with a consequent higher compression by the compressor 5. The back pressure in conduit 11 then increases with a consequent smaller quantity of air passing through the air turbine. In this case also, there is an automatic regulation of the operating conditions existing for the moment. The smaller discharge at lt operates to oppose a greater discharge at 9 by the increase in pressure. Moreover, the operator has at his disposal valves 10 and 12 to control the operation, and the constructor can readily dimension the air turbine and compressor 5 so that there will neither be an undue speed of this group nor an excessive load on the main compressor.

The additional compressor 5 illustrated in Fig. 2 is designed as a centrifugal compressor and the power engine 6 for driving the latter is an air-turbine. Compressor and turbine have one discharge branch 15 common to both arranged between the suction branch 16 of the additional compressor and the inlet branch 17 of the air turbine.

I claim:

1. A compressor installation, comprising in combination, at least one main compressor, at least one additional compressor adapted to work in series with said main compressor for the purpose of obtaining a higher pressure, and a driving engine for said additional compressor driven by a portion of the medium delivered by the main compressor, that portion expanding in the driving engine to the delivery pressure of the additional 'con'ipressor and being hereupo-n returned together with the medium delivered by the additional compressor to the 11121111 compressor.

2. A compressor installation, comprising in combination, a main compressor, an additional compressor, means interposed be.- tween said main compressor and said additional compressor and adapted to conduct the medium compressed in the additional compressor to said main compressor whereby the latter works in series with the formen a power engine adapted to drive said additional compressor, means adapted to conduct a portion of the medium delivered by said main compressor to said power engine to drive the latter by expanding to the delivery pressure of the additional compressor, and means adapted to return the medium expanded inthe power engine together with the medium delivered by the additional compressor to the main compressor.

3. A main compressor in combination with an air turbine and an additional compressor mounted on a shaft common to both, and acasing common to both, said turbine and additional compressor discharging into said 'casing and said casing connected in series with the main compressor.

4. A main compressor, in combination with an air turbine and an additional compressor mo'unted on a shaft common to both, and a casing common to both, said turbine and -additional compressor discharging into said casing and said casing connected in series with the main compressor, and said main compressor arranged to discharge a portion of the compressed medium delivered therefrom to said turbine.

5. A compressor installation comprising in combination, a main compressor having an intake and a. valve in said intiake, I at least one additional compressor, a driving engine, means to deliver a portion of the medium compressed by the main compressor to said engine, a valve cont-rolling said means, a connection common to said additional compressor and driving engine con nected to the intake of the main compressor, a valve in said connection, and a discharge between the main compressor and engine.

In testimony whereof I atiix my signature.

BENJAMIN GRAEMIGER.

lit) 

